The hypothesis of this Phase III clinical trial is that treatment for 24 weeks with a daily dosage of 450 IU of human interferon alpha is safe and will significantly increase stimulated saliva production compared to placebo in subjects with primary Sjogren's syndrome. The primary objective will be measured by changes in stimulated whole saliva production. Secondary objectives will be measured by 100mm visual analog scales and other patient questionnaires. Change from baseline will be calculated for all secondary objective variable. The other objective is safety. This will be met by comparing adverse event reports and changes in laboratory variables.